JP3370577B2 - Exhaust gas purification catalytic converter and manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile exhaust gas purifying converter excellent in durability and a manufacturing method thereof,
In particular, the present invention relates to a catalytic converter in which the winding property and the assembling property of an inorganic sealing material provided between a periphery of a catalyst holder and a metal shell on a catalyst carrier are improved.

[0002]

2. Description of the Related Art Conventionally, in a catalytic converter for purifying exhaust gas mainly mounted on a vehicle, as shown in FIG. 1, a catalyst holder 4 and a metallic shell 21 in a half-divided state for covering the outside of the catalyst holder 4 are used. , 22 and an inorganic sealant 3 and a metal net 5 disposed between them (clam shell type) and a composite of the inorganic sealant 3 and the metal net 5 on the outer periphery of the catalyst holder 4 as shown in FIG. There is known a product (exhaust manifold integrated type) in which a product wrapped around is cast into a cast iron shell. The catalyst holder 4 carries a catalyst such as platinum. As the catalyst holder 4, for example, a cordierite carrier having a honeycomb cross section is used.

Next, as the inorganic sealing material, a mixture of silica / alumina ceramic fibers, unexpanded vermiculite, an inorganic binder and an organic elastic material is formed into a sheet. The inorganic sealant 3 is used to prevent exhaust gas from leaking between the shell 2 and the catalyst holder 4.

[0004]

By the way, in recent years, the temperature of exhaust gas has risen remarkably due to high performance of automobiles and various laws and regulations. In the conventional catalytic converter structure shown in FIGS. 1 and 2, the inorganic seal is used. The heat resistance of the material is insufficient, and it is becoming difficult to secure sufficient sealing properties. It is considered that this is because the heat of exhaust gas deteriorates the expansion characteristics of the unexpanded vermiculite compounded in the above-mentioned inorganic seal layer, and the inorganic seal material is eroded by the pulse pressure of exhaust gas. ing.

In view of the above problems, the present inventors have used an inorganic sealing material obtained by vacuum-packing an arbitrary ceramic fiber simple substance with a polyethylene film having a thickness of 80 μm to provide a catalyst for purifying exhaust gas having excellent durability. Although we have developed a converter, in the above invention, when a single ceramic fiber alone is vacuum packed with polyethylene film, the gas barrier performance of the polyethylene film is low, so the thickness of the sealing material can be reduced in just a few hours. Immediately after that, there was a problem that the amount was increased to about twice and the winding property and assembling property on the catalyst holder were remarkably lowered.

In view of the above problems, the present invention proposes a catalytic converter and a manufacturing method using an inorganic sealing material which is excellent in durability and can be easily wound and assembled on a catalyst holder. .

[0007]

Means for Solving the Problems As a result of intensive studies made again to overcome the above problems, the present inventors have found that at least one surface of an organic film is provided with a vapor deposition film of SiO ₂ , Al ₂ O ₃ , Al or the like. The inventors have found that it is effective to use the formed composite film, and have developed the present invention. That is, the present invention comprises a catalyst holder, a metal shell covering the outside of the catalyst holder, and an inorganic sealing material interposed between the two,
The inorganic sealing material, the inorganic fiber mat-like material, the total Thickness having deposited film SiO _2, Al ₂ O ₃ or A l is deposited on at least one surface of the organic film in a range of 10 to 100 [mu] m a catalytic converter for purifying exhaust gases which is characterized by using what was depressurized packed in the composite film.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the inorganic fiber mat-like material which is a component of the inorganic sealing material is alumina,
Silica - alumina, it is preferable that any one or complexes of silica or glass. The packing density of the inorganic sealing material is adjusted to be 0.15 to 0.5 g / cm ³ . This has a packing density of 0.15 g / cm ³
This is because if it is smaller than the above value, a predetermined holding force cannot be obtained and the catalyst holding body may be displaced. On the other hand, the packing density is 0.5
If it is larger than g / cm ³ , the inorganic fiber may be broken and scattered due to high compressive stress after assembly, and the catalyst holder may be crushed. Therefore, the more preferable packing density of the inorganic sealing material is in the range of 0.2 to 0.4 g / cm ³ .

[0009] Next, the composite film which is also the inorganic sealant components, polyethylene, an organic film of polypropylene or polyethylene terephthalate as a base material, on at least one surface of such substrates, SiO _2, Al ₂
Has a vapor deposition film on which O ₃ or Al is vapor deposited, and has a total thickness of 10 to
It must be adjusted within the range of 100 μm.

Here, the reason for vapor depositing SiO ₂ , Al ₂ O ₃ , Al, etc. is that the presence of the vapor deposition film having a predetermined thickness in the composite film remarkably improves the gas barrier performance. The sealing material can maintain the state immediately after the decompression pack for a long time. The total thickness of the composite film is
It is preferable to use a material within the range of 10 to 100 μm. This is because when the thickness is less than 10 μm, the gas barrier performance and the pinhole resistance are insufficient, and when the thickness is more than 100 μm, the composite film itself becomes hard and the winding property around the catalyst support deteriorates. I will end up. Therefore, a more preferable thickness is in the range of 30 to 70 μm.

The deposition thickness of SiO ₂ , Al ₂ O ₃ , Al or the like is preferably adjusted within the range of 1 nm to 1 μm. This is because if the film thickness is less than 1 nm, it is difficult to maintain the state immediately after the reduced pressure pack because the thickness of the gas barrier layer is insufficient. On the other hand, when the thickness exceeds 1 μm, the vapor deposition film becomes hard and winding around the catalyst holder becomes difficult, and the vapor deposition film is liable to be cracked or broken, which may deteriorate reliability. Therefore, a more preferable vapor-deposited film is in the range of 10 to 100 nm.

Further, regarding the method for producing the above-mentioned inorganic sealing material, when the above-mentioned inorganic fiber mat-like material cut to a predetermined size is packed under reduced pressure using the above-mentioned composite film, the degree of vacuum is in the range of 500 to 755 mmHg. It is preferable to adjust and manufacture in the inside. If the pressure is less than 500 mmHg, the reduced pressure packed state is insufficient and residual air is contained, so that the winding property and the assembling property around the catalyst holder are deteriorated. On the other hand, if it is higher than 755 mmHg, the inorganic fiber mat-like material is densified in the reduced pressure packed state, and the flexibility of the mat is impaired, so that it becomes difficult to wind it around the catalyst carrier.

[0013]

【Example】

Example 1 An example of an exhaust gas purifying converter according to the present invention will be described below with reference to FIGS. As shown in the figure, the exhaust gas purifying converter 1 according to the present invention has a gap between a catalyst holder 4 made of cordierite having a honeycomb structure cross section and a metal shell 2 covering the outer peripheral surface of the catalyst holder 4, An inorganic sealing material having a packing density adjusted to 0.3 g / cm ³ is inserted. Here, as the inorganic sealing material, as shown in FIG. 4, polyethylene terephthalate is a base film on the upper and lower surfaces of an alumina fiber mat-shaped product 3 cut to a predetermined size, and one surface of this base film is used.
After the composite film 5 having a thickness of 50 μm and having SiO ₂ vapor deposited thereon is superposed, the outer peripheral portion of the mat is heat-sealed and, at the same time, it is vacuum-packed at a vacuum degree of 500 mmHg. The thickness of the SiO ₂ vapor deposition film 6 in this example was 100 nm.

The inorganic sealing material produced as described above is
After being left at room temperature for 1 month, it was used for the production of the exhaust gas purifying catalytic converter shown in FIG. 3, and as a result, there was no problem in winding and assembling the inorganic seal layer around the catalyst holder, and it was satisfactory.

Example 2 The same catalytic converter structure as in Example 1, except that the composite film was used as a base film, and Al ₂ O ₃ was vapor-deposited to a thickness of 100 nm on one side of the base film. As a result of changing and attempting production, there was no particular problem.
Also, as in Example 1, the inorganic seal layer was left at room temperature for one month, and the production was tried. As a result, there was no problem in winding and assembling the inorganic seal material around the catalyst holder, and it was good. It was

Comparative Example 1 The catalyst converter structure was the same as that of Example 1, but the composite film was replaced with a polyethylene terephthalate film having a thickness of 50 μm and not subjected to SiO ₂ vapor deposition, and the production was tried. There is no particular problem if the above inorganic sealing material is used, but the inorganic sealing material is swollen 1 hour after the reduced pressure packing, and it becomes difficult to wind the inorganic sealing material around the catalyst holder.

[0017]

As described above, according to the present invention,
As the airtight composite film of the sealing layer, which is obtained by vapor-depositing SiO ₂ or the like on the inside of the plastic sheet, the durability of the sealing layer is improved and the vacuum pack can be surely made, and further, the flexibility is good. Mounting in a metal shell,
That is, winding and assembling on the catalyst holder are facilitated.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a conventional clamshell type exhaust gas purifying catalytic converter.

FIG. 2 is an exploded perspective view of a conventional exhaust manifold-integrated catalytic converter for purifying exhaust gas.

FIG. 3 is a sectional view of a catalytic converter.

FIG. 4 is a partial perspective view illustrating the structure of the airtight composite film according to the present invention.

[Explanation of symbols]

1 Exhaust Gas Purification Catalyst Converter 2 Metal Shell 3 Seal Mat 4 Catalyst Holder 5 Metal Net 6 SiO ₂ Evaporation Film 7 Plastic Film 21, 22 Metal Shell 23 Cast Iron Shell

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Keiichi Sakashita 3-200, Kawama-cho, Ogaki-shi, Gifu Ibiden Co., Ltd., Kawama Plant (72) Inventor, Tao Tamura, Toyota-cho, Aichi Prefecture Toyota Motor Corporation Stock In-house (56) References JP-A-50-112615 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F01N 3/28

Claims (3)

(57) [Claims] 1. A catalyst holder, a metal shell for covering the outside of the catalyst holder, and an inorganic sealant interposed between the catalyst holder and the inorganic sealant. the use of those total thickness having deposited film SiO _2, Al ₂ O ₃ or a l is deposited on at least one surface of the organic film is vacuum packed in the composite film in the range of 10 to 100 [mu] m A characteristic exhaust gas purification catalytic converter. 2. A top quinic machine fiber mat-like material is alumina,
Silica - alumina, is any one or a complex of the silica or glass, packing density 0.15~0.5g / cm ³
Der those adjusted is, the composite fill beam is to polyethylene, the more becomes the organic film either polypropylene or polyethylene terephthalate <br/> over preparative and substrate, SiO
A vapor-deposited film consisting of ₂ , Al ₂ O ₃ or Al has a film thickness of 1
The exhaust gas purifying catalytic converter according to claim 1, wherein the catalytic converter is adjusted to have a nm to 1 μm. 3. The inorganic sealing material, when the inorganic fiber mat-like material cut to a predetermined size is packed under reduced pressure using the composite film, the degree of vacuum is 500 to 755 mmHg.
The process according to claim 1 for purifying exhaust gas catalytic converter according to adjusted to the range of characterized der Rukoto those produced.